introduction
A pressure sensor is a sensor that converts pressure signals into electrical signals. Its working principle is to measure pressure by utilizing the deformation of a sensitive element. Pressure sensors are widely used in industries such as industry, scientific research, and medicine, including petroleum, chemical, power, aviation, aerospace, and biomedicine. Accuracy is one of the important indicators for evaluating the performance of a pressure sensor, as it directly affects the reliability and accuracy of the measurement results.
Working principle of pressure sensor
The working principle of a pressure sensor is to measure pressure by utilizing the deformation of a sensitive element. When pressure is applied to the sensitive element, the element deforms, and the magnitude of the deformation is proportional to the applied force. The deformation of the sensitive element is converted into an electrical signal by a conversion element, and after amplification, filtering, analog-to-digital conversion, etc., a digital signal or analog signal is output.
Based on the type of sensing element, pressure sensors can be classified into the following categories:
Strain gauge pressure sensor: It uses strain gauges to measure the deformation of the sensitive element, and then converts the resistance strain into an electrical signal.
Capacitive pressure sensor: It measures pressure by utilizing changes in capacitance. When pressure is applied to the sensitive element, the capacitance value changes.
Piezoelectric pressure sensors: These sensors use the piezoelectric effect of piezoelectric materials to measure pressure. When pressure is applied to the sensitive element, an electric charge is generated.
Photoelectric pressure sensor: It uses the photoelectric effect to measure pressure. When pressure is applied to the sensitive element, it will cause the refraction or reflection of light.
Magnetoelectric pressure sensor: It uses the magnetoelectric effect to measure pressure. When pressure is applied to the sensitive element, it causes a change in the magnetic field.
Accuracy class of pressure sensor
The accuracy class of a pressure sensor refers to the magnitude of its measurement error, usually expressed as a percentage or absolute value. A higher accuracy class indicates a smaller measurement error and more accurate measurement results. Pressure sensor accuracy classes are typically divided into the following categories:
0.01%FS: Full scale with a measurement error of less than 0.01%.
0.02%FS: Full scale with a measurement error of less than 0.02%.
0.05%FS: Full scale with a measurement error of less than 0.05%.
0.1%FS: Full scale with a measurement error of less than 0.1%.
0.2%FS: Full scale with a measurement error of less than 0.2%.
0.5%FS: Full scale with a measurement error of less than 0.5%.
1%FS: Full scale with a measurement error of less than 1%.
2%FS: Full scale with a measurement error of less than 2%.
5%FS: Full scale with a measurement error of less than 5%.
10%FS: Full scale with a measurement error of less than 10%.
Classification of pressure sensor errors
The error of a pressure sensor can be divided into absolute error, relative error, and total error.
Absolute error: refers to the difference between the measured value and the true value, usually expressed in absolute value.
Relative error: refers to the ratio of the absolute error to the true value, usually expressed as a percentage.
Total error: refers to the sum of all errors that a pressure sensor may produce during the measurement process, including systematic errors, random errors, etc.
Method for calculating pressure sensor error
5.1 Calculation method of absolute error
The formula for calculating absolute error is:
Absolute error = Measured value - True value
For example, if a pressure sensor measures 100 Pa, but the actual value is 98 Pa, then the absolute error is 2 Pa.
5.2 Calculation method of relative error
The formula for calculating relative error is:
Relative error = (Absolute error / True value) × 100%
For example, if the absolute error of a pressure sensor is 2 Pa and the true value is 98 Pa, then the relative error is (2 / 98) × 100% ≈ 2.04%.
5.3 Calculation method for total error
The calculation of total error is relatively complex, requiring consideration of multiple factors such as systematic errors and random errors. The formula for calculating total error is:
Total error = √((systematic error)^2 + (random error)^2 + ...)
For example, if the systematic error of a pressure sensor is 1 Pa and the random error is 0.5 Pa, then the total error is √((1)^2 + (0.5)^2) ≈ 1.11 Pa.
